pmap.ex

defmodule Pmap do
  @moduledoc """
  Documentation for Pmap.
  """

  def pmap(list, func) do
    pmap(self(), 0, list, func, [])
  end

  @doc false
  defp pmap(_, _, [], _, pid_list) do
    pid_list
    |> receive_result([])
    |> IO.inspect()
    |> Enum.sort()
    |> Enum.map(fn {_, v} -> v end)
  end

  defp pmap(task_owner, index, [head | tail], func, pid_list) do
    pid = spawn(fn ->
      Process.sleep(Enum.random(1..1000))
      send(task_owner, {self(), index, func.(head)})
    end)
    pmap(task_owner, index + 1, tail, func, [pid | pid_list])
  end

  @doc false
  defp receive_result([], res_list), do: res_list
  defp receive_result(pid_list, res_list) do
    receive do
      {pid, index, value} ->
        if Enum.member?(pid_list, pid) do
          receive_result(List.delete(pid_list, pid), [{index, value} | res_list])
        else
          receive_result(pid_list, res_list)
        end
    end
  end

  # __end_of_module__
end